Do any of you know of a list of all entities with images of each entity shown also so that I can visualise things before i try pasting them into monuments so dont have be like a trial and error thing?

Thanks in advance.

Just put it in your hotbar like you are going to place it normally. when it looks good simply run maspawn command (no parm/entity needed)

How do I add something like a rock formation into my hotbar?

You can´t. You could install rustedit and place them there and make screenshots for your own list or you take a look in it´s install folder for example, for stones
/PreviewImages/assets/content/nature/rocks

There you find images of the cliffs you can spawn with MonumentAddons

/maspawn admin_cliff_low_arc
/maspawn admin_cliff_medium_arc_arid_small
/maspawn admin_rock_clutter_medium_d
/maspawn admin_rock_formation_medium_a
/maspawn admin_rock_formation_small_c
/maspawn admin_rock_quarry_small_a

Ok thanks for the support appreciated.